Horses Broodmare Care


Ideally mares should be checked for pregnancy two weeks after ovulation and again at 30 and 90 days of pregnancy. The sooner you know which mares are not pregnant the sooner you can address the reasons why they are not. If you did not previously check for pregnancy, work with your veterinarian to do so now.

                                                        Sequin II With Foal 2005

A number of factors can prevent a mare from becoming pregnant and maintaining the pregnancy. The easiest factors to address are management practices.

Open mares, especially mares that have been barren for more than two years, should be examined by a veterinarian to determine if reproductive problems exist.

Mares that do not show strong signs of estrus (heat) may be overlooked and assumed in foal.

Lower pregnancy rates can result from breeding only in the early part of estrus. Timely insemination is critical for conception. Mares typically ovulate during the latter part of estrus and most semen only remains viable for 72 hours in the uterus. Research has demonstrated that breeding a mare every other day from the day she will stand to be mounted until she refuses the stallion is the best protocol for natural service.

Teasing mares for only one cycle after they have been bred can cause you to overlook open mares.

The greatest percentage of mares that do not settle is due to early embryonic loss.

Uterine infection, which can be present before breeding or can be caused by breeding makes embryo survival impossible. Some mares are more prone to these types of infections due to poor reproductive conformation. Reproductive conformation is determined by looking at the angle of a mare’s vulva. The more a mare’s vulva slopes inward toward the anus the greater the chance fecal material will enter the vagina and lead to uterine infection. To reduce the chance of this type of uterine infection, check with your veterinarian about performing a Caslick’s procedure and the extra management needed.

Poor reproductive conformation is not limited to the external genitalia. The vagina often slopes forward causing urine to pool in the uterus resulting in uterine infection.

Uterine infections can be determined by an ultrasound examination.

Consult your veterinarian about any mare that has bred, not maintained the pregnancy and subsequently remained barren for two or more years.

Rhinopneumonitis (equine herpesvirus type 1) is the leading cause of late term abortion in mares. This virus is transmitted via respiratory secretions and/or airborne viral particles. Good management practices will aid in preventing this disease in your broodmare band.

Do not introduce new mares into the herd after the 5th month of pregnancy.

Keep your horses that travel to shows, away from your broodmares.

The best defence against infection is vaccination using a killed virus EVH-1 vaccine. Use of a vaccine containing a live virus has been known to cause abortion in mares. There are two killed virus products available which require multiple boosters – read and follow label directions. Take a preventative approach — waiting to vaccinate until a mare aborts will not allow time to build immunity in other mares.

Consult your veterinarian for information on diseases endemic to you area. Some of the common vaccines given to broodmares include eastern and western equine encephalomyelitis, tetanus, influenza, equine pneumonitis, and Potomac horse fever.

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